Fiber alignment process using cornercube offset tool

ABSTRACT

A system and method for aligning optical fibers that takes into account variations due to temperature changes and other nonrandom systemic effects. The system includes an alignment tool having a plurality of internal reflection surfaces and located below a vision plane of the first one of the pair of optical fibers, and an optical detector to receive an indirect image of a bottom surface of the first optical fiber through the alignment tool, such an offset between the first optical fiber and the optical detector is determined based on the indirect image received by the optical detector. The method comprises the steps of providing a cornercube offset tool having a plurality of total internal reflection surfaces below a vision plane of the first optical fiber, and receiving an indirect image of the first optical fiber through the cornercube offset tool.

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/912,024 filed on Jul. 24, 2001.

FIELD OF THE INVENTION

[0002] This invention relates generally to the use of machine visionsystems for semiconductor chip bonding/attaching devices. Morespecifically, the present invention relates to the use of a corner cuberetro-reflector as an offset alignment tool that acquires indirectimages of optical fibers optic during the alignment process when thesame lie outside the view of the imaging system. From such images,coordinate information on position can be obtained and any positionaloffset from reference position of the fiber optic alignment tool due todeviations caused by thermal change or other nonrandom systemic errorscan be taken into account for correct alignment and placement of opticalfibers with respect to other optical fibers or fiber opticdetectors/devices/elements.

BACKGROUND OF THE INVENTION

[0003] The fabrication of electronic assemblies, such as integratedcircuit chips and fiber optic cables, requires alignment inspection ofthe device at various phases of the fabrication process. Such alignmentinspection procedures utilize vision systems or image processing systems(systems that capture images, digitize them and use a computer toperform image analysis) to align devices and guide the fabricationmachine for correct placement and/or alignment of components.

[0004] In conventional systems, post attach inspection is used todetermine if changes in fabrication machine position are necessary toeffect proper placement and/or alignment. As such, these conventionalsystems can only compensate for misalignment after such improperalignment is made, thereby negatively effecting yield and throughput.These conventional systems have additional drawbacks in that they areunable to easily compensate for variations in the system due to thermalchanges, for example, requiring periodic checking of completed devicesfurther impacting device yield and negatively impacting manufacturingtime.

[0005] In conventional systems the vision system (shown in FIG. 11)consists of two image devices, a first image device 1104 placed belowthe optical plane 1112 and views objects upward and a second imagedevice 1102 placed above the optical plane and views objects downward.These conventional systems have drawbacks, in that in addition torequiring more than one image device, they are unable to easilycompensate for variations in the system due to thermal changes, forexample.

SUMMARY OF THE INVENTION

[0006] In view of the shortcomings of the prior art, it is an object ofthe present invention to provide a system and method for aligningoptical fibers using a vision system that takes into account variationsdue to temperature changes and other nonrandom systemic effects.

[0007] The present invention is a vision system for use in aligningoptical fibers. The system comprises an alignment tool having aplurality of internal reflection surfaces, the alignment tool locatedbelow a vision plane of the first optical fiber; and an optical detectorto receive an indirect image of a bottom surface of the first opticalfiber through the alignment tool.

[0008] According to another aspect of the invention, the vertex of thealignment tool is located at a position about midway between the opticalaxis of the optical detector and the optical axis of the first opticalfiber.

[0009] According to a further aspect of the invention, the alignmenttool comprises a cornercube offset tool.

[0010] According to still another aspect of the invention, the focalplane of the vision system is positioned at or above the alignment tool.

[0011] According to yet another aspect of the present invention, thesystem includes a lens positioned between the alignment tool and i) theoptical detector and ii) the first optical fiber.

[0012] According to still another aspect of the present invention, thesystem includes a first lens positioned between the optical detector andthe alignment tool and a second lens positioned between the firstoptical fiber and the alignment tool.

[0013] According to a further aspect of the present invention, the firstlens and the second lens are located at or below the image plane.

[0014] According to yet a further aspect of the present invention, thereflecting surfaces are three mutually perpendicular faces.

[0015] According to yet another aspect of the present invention, theangle between each of the internal reflective surfaces and the topsurface of the cornercube offset tool is about 45°.

[0016] According to still another aspect of the invention, the opticaldetector is a CCD camera.

[0017] According to yet another aspect of the invention, the opticaldetector is a CMOS imager.

[0018] According to yet a further aspect of the invention, the opticaldetector is a position sensitive detector.

[0019] According to an exemplary method of the present invention, acornercube offset tool is positioned below a vision plane of the firstoptical fiber; a lens is positioned between i) the first optical fiberand the cornercube offset tool and ii) between the optical imager andthe cornercube offset tool; and the first optical fiber is viewedindirectly through the cornercube offset tool and the lens.

[0020] These and other aspects of the invention are set forth below withreference to the drawings and the description of exemplary embodimentsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is best understood from the following detaileddescription when read in connection with the accompanying drawing. It isemphasized that, according to common practice, the various features ofthe drawing are not to scale. On the contrary, the dimensions of thevarious features are arbitrarily expanded or reduced for clarity.Included in the drawing are the following Figures:

[0022]FIG. 1 is a perspective view of an exemplary embodiment of thepresent invention;

[0023]FIG. 2A is a side view of image ray traces according to a firstexemplary embodiment of the present invention;

[0024]FIG. 2B is a side view of image ray traces according to a secondexemplary embodiment of the present invention;

[0025]FIG. 3 is a perspective view of image ray traces according to anexemplary embodiment of the present invention;

[0026]FIGS. 4A and 4B are perspective and side views, respectively, ofan exemplary embodiment of the present invention;

[0027]FIG. 5 illustrates the telecentricity of an exemplary embodimentof the present invention;

[0028]FIG. 6 is a detailed view of an exemplary retroreflectivecornercube offset tool according to the present invention;

[0029] FIGS. 7A-7C illustrate the effect of tilt about the vertex of thecornercube tool of the exemplary vision system;

[0030] FIGS. 8A-8C illustrate the effect of tilt about the X and Y axisof the exemplary vision system;

[0031]FIG. 9 is a side view of image ray traces according to a thirdexemplary embodiment of the present invention;

[0032] FIGS. 10A-10E are various views of a fourth exemplary embodimentof the present invention;

[0033]FIG. 11 is a vision system according to the prior art;

[0034]FIG. 12 is an illustration of a fifth exemplary embodiment of thepresent invention; and

[0035] FIGS. 13A-13D are various views of a sixth exemplary embodimentof the present invention.

DETAILED DESCRIPTION

[0036] The entire disclosure of U.S. patent application Ser. No.09/912,024 filed on Jul. 24, 2001 is expressly incorporated by referenceherein

[0037] Referring to FIG. 1 a perspective view of an exemplary embodimentof the present invention is shown. The system is included in wirebonding machine 100, and employs a cornercube 106, having a plurality ofinternal reflection surfaces (best shown in FIG. 6), located at or belowimage plane 112 of bonding tool 104.

[0038] In an exemplary embodiment, cornercube offset alignment tool 109(comprising cornercube 106 and lens elements 108, 110), has a total ofthree internal reflection surfaces, 218, 220, and 221 (best shown inFIG. 6 and described below). In another exemplary embodiment, cornercube106 may have a plurality of total internal reflective surfaces. In oneexemplary embodiment, cornercube 106 is formed from fused silica,sapphire, diamond, calcium fluoride or other optical glass. Note,optical quality glass, such as BK7 made by Schott Glass Technologies ofDuryea, Pa., may also be used. Note also that materials for cornercube106 can be selected for maximum transmission with respect to the desiredoperating wavelength.

[0039] Optical imaging unit 102, such as a CCD imager, CMOS imager or acamera, for example, is mounted above image plane 112 in order toreceive an indirect image of bonding tool 104 through cornercube offsetalignment tool 109. In another exemplary embodiment, a positionsensitive detector (PSD), such as that manufactured by Ionwerks Inc., ofHouston, Tex., may also be used as optical imaging unit 102. In such anembodiment, when the hole in bonding tool 104 is illuminated, such as byusing an optical fiber for example, the PSD can be utilized to recordthe position of the spot of light exiting bonding tool 104. It is alsocontemplated that the PSD may be quad cell or bi-cell detector, asdesired.

[0040] In the exemplary embodiment, the focal point of the vision system(coincident with imaginary plane 211 shown in FIG. 2A) is located abovebottom surface 223 (shown in FIG. 2A) of cornercube 106. In addition,the exemplary embodiment includes two preferably identical lens elements108, 110 located at or below image plane 112. Another embodiment, shownin FIG. 2B, includes a single lens element 205 located below image plane112 and in line with optical axes 114, 116. Hereinafter, the combinationof cornercube offset tool 106, and lens elements 108, 110 (or lenselement 205) will be referred to as assembly 109.

[0041] Image plane 112 of cornercube 106, including lens elements 108,110, is positioned at the object plane of optical imaging unit 102. Inother words, the object plane of cornercube 106 and lens elements 108,110 are aligned to bonding tool 104 which also lies in image plane 112.In the exemplary embodiment, lens elements 108, 110 (or 205) preferablyhave a unitary magnification factor. First lens element 108 ispositioned in a first optical axis 114 between bonding tool 104 andcornercube 106. Second lens element 110 is substantially in the sameplane as that of first lens element 108 and is positioned in a secondoptical axis 116 between optical imaging unit 102 and cornercube 106. Inone exemplary embodiment, first and second optical axes 114 and 116 aresubstantially parallel to one another, and are spaced apart from onanother based on specific design considerations of bonding machine 100.In one exemplary embodiment the distance 118 between first optical axis114 and second optical axis 116 is about 0.400 in. (10.160 mm.) althoughdistance 118 may be as small as about 0.100 in. (2.54 mm) depending ondesign considerations related to the bonding machine.

[0042]FIG. 2A is a detailed side view of image ray traces andillustrates the general imaging concept of an exemplary embodiment ofthe present invention. In FIG. 2A, exemplary ray traces 210, 214 areseparated for clarity to illustrate the relative immunity of theresultant image due to positional changes. The same distance alsoseparates the image points because lens elements 108, 110 serve asunitary magnification relays. FIG. 2A also demonstrates how changes inthe bonding tool 104 position are compensated for. For example, onceconventional methods have been used to accurately measure the distancebetween imaging unit 102 and bonding tool 104 (shown in FIG. 1), thepresent invention is able to compensate for changes in the bonding tool104 offset position 222 due to changes in the system. The location ofbonding tool 104 can be accurately measured because cornercube offsettool 106 images bonding tool 104 onto image plane 112 of the opticalsystem.

[0043] The reference position of bonding tool 104 is shown as areflected ray which travels from first position 202 along first opticalaxis 114 (shown in FIG. 1), as direct image ray bundle 210 from firstposition 202 through first lens element 108. Direct image ray bundle 210continues along first optical axis 114 where it then passes through topsurface 226 of cornercube 106 onto first internal reflection surface218. Direct image ray bundle 210 is then reflected onto second internalreflection surface 220, which in turn directs it onto third internalreflective surface 221 (best shown in FIG. 3). Next, direct image raybundle 210 travels back through top surface 226 of cornercube 106 asreflected image ray bundle 212 along the second optical axis 116 (shownin FIG. 1) and through second lens element 110 to image plane 112. It isreflected image ray bundle 212 that is detected by imaging unit 102 asimage 204.

[0044] Consider now that the position of bonding tool 104 is displacedby a distance 222 due to a variation in system temperature, for example.As shown in FIG. 2A, the displaced image of bonding tool 104 is shown asposition 206 and imaged along the path of second position ray trace 214.As shown in FIG. 2A, direct image ray bundle 214 travels along a pathsimilar to that of direct image ray bundle 210 from first position 202.Second position 206 image travels as a direct image ray bundle 214,through first lens element 108. Direct image ray bundle 214 then passesthrough top surface 226 of cornercube 106 onto first internal reflectionsurface 218. Direct image ray bundle 214 is then reflected onto secondinternal reflection surface 220, which in turn directs it onto thirdinternal reflection surface 221 (best shown in FIG. 3). Next, directimage ray bundle 214 travels through top surface 226 of cornercube 106as reflected image ray bundle 216 and through second lens element 110 toimage plane 112. Reflected image ray bundle 216 is viewed as a reflectedimage by imaging unit 102 as being in second position 208. Although theabove example was described based on positional changes along the Xaxis, it is equally applicable to changes along the Y axis.

[0045] As illustrated, the original displacement of bonding tool 104,shown as offset position 222, is evidenced by the difference 224 in themeasured location of bonding tool 104 at second position 208 withrespect to reference location 204. As evidenced by the aboveillustration, a positional shift in assembly 109 does not affect thereflected image as viewed by imaging unit 102. In other words, assembly109 of the present invention may be translated along one or both the Xand Y axes such that the image of the bonding tool 104 appearsrelatively stationary to imaging unit 102. There will be some minimaldegree of error, however, in the measured position of bonding tool 104due to distortion in the lens system (discussed in detail below).

[0046] Referring again to FIG. 2A, vertex 228 (shown in phantom) ofcornercube offset alignment tool 109 is located at a positionapproximately midway between first optical axis 114 and second opticalaxis 116. To facilitate mounting of cornercube 106, a lower portion 235of the cornercube may be removed providing bottom surface 223, which maybe substantially parallel to top surface 226. Removal of lower portion235 does not affect the reflection of image rays since the image raysemanating from image plane 112 do not impinge upon bottom surface 223.

[0047] Exemplary cornercube 106 comprises top surface 226, firstreflective surface 218, bottom surface 223, second reflective surface220, and third reflective surface 221. If top surface 226 is set suchthat optical axes 114, 116 are normal to top surface 226, firstreflective surface 218 will have a first angle 230 of about 45° relativeto top surface 226, and a second angle 234 of about 135° relative tobottom surface 223. Likewise, ridgeline 225 (formed by the intersectionof second and third reflective surfaces 220 and 221) has similar angles232 and 236 relative to top surface 226 and bottom surface 223,respectively. In addition, second and third reflective surfaces 220 and221 are orthogonal to one another along ridgeline 225. In the exemplaryembodiment, bottom surface 223 of cornercube 106 may be used as amounting surface if desired. It should be noted, however, that it is notnecessary to form top surface 226 so that the image and reflected raysare normal thereto. As such, the corner cube will redirect the incidentlight or transmit image of bonding tool 104 parallel to itself with anoffset equal to 118.

[0048] The present invention can be used with light in the visible, UVand IR spectrum, and preferably with light having a wavelength thatexhibits total internal reflection based on the material from whichcornercube 106 is fabricated. The material selected to fabricatecornercube offset alignment tool 109 is based on the desired wavelengthof light which the tool will pass. It is contemplated that cornercubeoffset alignment tool 109 may be fabricated to handle a predeterminedrange of light wavelengths between the UV (1 nm) to the near IR (3000nm). In a preferred embodiment, the range of wavelength of light may beselected from between about i) 1 and 400 nm, ii) 630 and 690 nm, andiii) 750 and 3000 nm. Illumination may also be provided by ambient lightor by the use of an artificial light source (not shown). In oneexemplary embodiment, typical optical glass, having an index ofrefraction of 1.5 to 1.7, may be used to fabricate cornercube 106. Note,the index of refraction is based upon the material chosen for maximumtransmission at the desired operating wavelength. In one embodiment,cornercube offset alignment tool 109 has an index of refraction of about1.517.

[0049]FIG. 3 is a perspective view of image ray traces according to anexemplary embodiment of the present invention translated in a directionperpendicular to the separation of lens elements 108, 110. The sameimage properties shown in FIG. 2A are also evident in FIG. 3. Forexample, the reference position of bonding tool 104 is represented byfirst position 302 and its image 304 is viewed as a first direct imageray 310 which travels along first optical axis 114 through first lenselement 108; passes through top surface 226 of cornercube 106; strikesfirst reflective surface 218 of cornercube 106; travels throughcornercube 106 in a path parallel to top surface 226; strikes secondreflective surface 220; strikes third reflective surface 221 beforeexiting the cornercube 106 through top surface 226 and travels alongsecond optical axis 116 through second lens element 110 onto image plane112 and viewed by imaging unit 102 at position 304. Positionaldisplacement of bonding tool 104 is also shown in FIG. 3 and isillustrated by the path of the ray traces 314, 316 from second position306 to second viewed position 308.

[0050] FIGS. 4A-4B are perspective and side views, respectively, of anexemplary embodiment of the present invention illustrating lens elements108, 110 and cornercube 106. The two lens elements 108, 110 (or 205) arepreferably doublets located above the cornercube 106 based on theirfocal distance from image plane 112 and imaginary plane 211. Doubletsare preferred based on their superior optical qualities. As illustratedin FIGS. 4A-4B, an exemplary embodiment of cornercube 106 has threeinternal reflective surfaces, 218, 220 and 221. As shown in FIG. 4B, theexterior edges of lens elements 108, 110 and cornercube 106 arecoincident with one another.

[0051]FIG. 5 illustrates the telecentricity of an exemplary embodimentof the image system of the present invention. As shown in FIG. 5, lenselements 108, 110 produce a unitary magnification and are arrangedrelative to cornercube 106 such that the telecentricity of the machinevision system is maintained. Note that front focal length 502 from lenselement 108 to vertex 228 of cornercube 106 is equal to front focal 502from lens element 110 to vertex 228 of cornercube 106. Note also, thatback focal length 504 from lens element 108 to image plane 112 is equalto back focal length 504 from lens element 110 to image plane 112.

[0052]FIG. 6 is a detailed view of an exemplary cornercube 106 of thepresent invention. Note that internal reflection surface, 218 andridgeline 225 allow an image of bonding tool 104 to be translated in theX and Y directions. Note also, that the surfaces of cornercube 106 arepreferably ground so that a reflected beam is parallel to the incidentbeam to within 5 arc seconds.

[0053] As shown in FIG. 6, surfaces 220 and 221 are orthogonal to oneanother along ridgeline 225. In addition, the angle between ridgeline225 and surface 218 is about 90°. Furthermore, surface 218 and ridgelineform an angle of 45° relative to top surface 226 and bottom surface 223.Note also, that surfaces, 218, 220, and 221 meet to form triangularshaped bottom surface 223, which may be used to facilitate mounting ofcornercube 106.

[0054] FIGS. 7A-7C illustrate the effect of tilt about the orthogonal ofcornercube offset alignment tool 109 in an exemplary vision system. FIG.7A is an overhead view of lens elements 108, 110 and cornercube 106.Exemplary image origins, 702, 704, 706, and 708 correspond to theposition of image ray traces 210, 214 (shown in FIG. 2A). Note thatoptic axis position 710 corresponds to the position where the image ofbonding tool 104 (shown in FIG. 1) would be if cornercube 106 was nottilted along the Z axis.

[0055] FIGS. 7B-7C are graphs of the effect of tilt around the Z axis interms of tilt in arc minutes vs. error in microns. FIG. 7B shows theeffect of tilt around the Z axis versus error and image location alongthe Y axis. FIG. 7C shows the effect of tilt around the Z axis versuserror and image location along the X axis.

[0056] FIGS. 8A-8C illustrate the effect of tilt about the X and Y axisof the exemplary vision system. FIG. 8A is an additional side view ofexemplary image ray traces 210, 212, 214, 216. In FIG. 8A, arrow 804 anddot 802 are used to depict the X and Y axes, respectively.

[0057] FIGS. 8B-8C are graphs of the effect of tilt around the X and Yaxes in terms of tilt in arc minutes vs. error in microns. FIG. 8B showsthe effect of tilt around the X axis versus error and image locationalong the Y axis. FIG. 8C shows the effect of tilt around the Y axisversus error and image location along the X axis.

[0058]FIG. 9 is a detailed side view of image ray traces according to athird exemplary embodiment of the present invention. In FIG. 9, thereference position of bonding tool 104 is shown as a reflected ray whichtravels from first position 914 (on image plane 112) along first opticalaxis 114 (shown in FIG. 1), as direct image ray bundle 922 from firstposition 914 through lens element 902. Note that in this exemplaryembodiment, lens element 902 has a relatively planar, upper surface 904and a convex lower surface 906. Direct image ray bundle 922 continuesalong first optical axis 114 where it then passes through upper surface904 of lens element 902, and in turn through convex surface 906. Directimage ray bundle 922 is then reflected onto total reflective surface908. In a preferred embodiment, total reflective surface 908 is amirror. Next, direct image ray bundle 922 travels back through lenselement 902 as reflected image ray bundle 920 along second optical axis116 (shown in FIG. 1) and onto image plane 112. It is reflected imageray bundle 920 that is detected by imaging unit 102 (shown in FIG. 1) asimage 912. Similarly, positional displacement of bonding tool 104 isalso shown in FIG. 9 and is illustrated by the path of direct image raybundles 918, 924 from second position 910 to second viewed position 916.

[0059] FIGS. 10A-10E illustrate a further embodiment of the presentinvention. In this exemplary embodiment, a cornercube alignment tool isused to improve the accuracy of alignment of fibers, such as opticalfibers 1008 and 1009. As in the previous exemplary embodiment, the useof a corner cube offset tool allows for the use of a single opticaldetector instead of the conventional multiple detector systems.

[0060] Referring to FIG. 10A, the exemplary embodiment includescornercube 1014, lenses 1016, 1018, dark field illumination systems1020, 1021 (which are well known to those practicing the art) toilluminate the fiber cladding edge 1010, 1011 of fiber cores 1012, 1013,respectively (which in turn produces reflections 1024, 1025 to outlinecladding edges 1010, 1011), and optical detector 1002. In this exemplaryembodiment, downward facing fiber 1008 is viewed by downward lookingoptical detector 1002, such as a camera (i.e., a substrate camera).Downward looking optical detector 1002 detects the emission of light1022 from fiber core 1012 and is then be able to determine the properoffset 1027 between the optical fiber centerline 1023 and central ray1029 of downward looking optical detector 1002. As is further shown inFIG. 10A, downward facing fiber 1008 and optical detector 1002 areoffset from one another by predetermined distance 1006.

[0061]FIG. 10B is a plan view of the exemplary embodiment illustrated inFIG. 10A illustrating the relative positions of lenses 1016 and 1018,and cornercube 1014.

[0062] In FIG. 10C, downward looking optical detector 1002 and downwardfacing fiber 1008 are then repositioned such that central ray 1029 ofdownward looking optical detector 1002 is aligned with fiber centerline1031 of upward facing fiber 1009. Once again dark field illuminationsystem 1021 is used to illuminate upward facing fiber 1009 forrecognition by the vision system to ensure proper alignment with opticaldetector 1002.

[0063] Next, and as shown in FIG. 10D, optical detector 1002 anddownward facing fiber 1008 are again repositioned based on the offset1027 determined during the process discussed above with respect to FIG.10A. As a result downward facing fiber 1008 and upward facing fiber 1009are aligned with one another.

[0064] As shown in FIG. 10E, optical fibers 1008 and 1009 are thenjoined using conventional techniques, such as fusing the fibers togetherusing radiation (not shown), or mechanical means, for example.

[0065]FIG. 12 illustrates yet a further embodiment of the presentinvention. In this exemplary embodiment, a cornercube alignment tool isused to align individual fibers (sub-fibers) 1202 a of a fiber opticsplitter 1200 with respective individual optical fibers 1008, etc. As inthe previous exemplary embodiment, the use of a corner cube offset toolallows for the use of a single optical detector instead of theconventional multiple detector systems. As the steps leading up toalignment and coupling of optical fiber 1008 and sub-fiber 1202 aresimilar to the above exemplary embodiment, they are not repeated here.

[0066] Once the first sub-fiber is aligned with single fiber 1008, theprocess is repeated for a further sub-fiber, such as 1202 b, and anothersingle fiber (not shown).

[0067] Of course the exemplary embodiment is not limited to the fiberoptic bundle of a fiber optic splitter being below optical detector1002. The embodiment also contemplates that the relative positions offiber optic bundle 1200 and optical fiber 1008 are reversed, such thatfiber optic bundle 1200 is positioned above cornercube 1014.

[0068] FIGS. 13A-13D illustrate a further embodiment of the presentinvention. In this exemplary embodiment, a cornercube alignment tool isused to improve the accuracy of alignment of an optical fiber 1008 witha circuit element, such as a detector 1302. In FIG. 13A, exemplarydetector 1302 is part of an array 1300, although the invention is not solimited. It is also contemplated that circuit element 1302 may be adiode, such as a photodiode or an emitter of optical radiation. As inthe previous exemplary embodiments, the use of a corner cube offset toolallows for the use of a single optical detector instead of theconventional multiple detector systems.

[0069] Referring to FIG. 13A, the exemplary embodiment includescornercube 1014, lenses 1016, 1018, dark field illumination system 1020(which is well known to those practicing the art) to illuminate thefiber cladding edge 1010 of fiber core 1012 (which in turn producesreflections 1024 to outline cladding edge 1010), and optical detector1002. In this exemplary embodiment, downward facing fiber 1008 is viewedby downward looking optical detector 1002, such as a camera (i.e., asubstrate camera). Downward looking optical detector 1002 detects theemission of light 1022 from fiber core 1012 and is then be able todetermine the proper offset 1027 between the optical fiber centerline1023 and central ray 1029 of downward looking optical detector 1002. Asis further shown in FIG. 10A, downward facing fiber 1008 and opticaldetector 1002 are offset from one another by predetermined distance1006.

[0070] In FIG. 13B, downward looking optical detector 1002 and downwardfacing fiber 1008 are then repositioned such that central ray 1029 ofdownward looking optical detector 1002 is aligned with opticalcenterline 1304 of detector 1302. It is understood that opticalcenterline 1304, may not necessarily coincide with the physical centerof detector 1302, but rather is dependant on the layout of theparticular detector 1302. In this case the determination of opticalcenterline 1304 may be accomplished by the location of the center of theactive sensing area of the detector.

[0071] Next, and as shown in FIG. 13C, optical detector 1002 anddownward facing fiber 1008 are again repositioned based on the offset1027 determined during the process discussed above with respect to FIG.13A. As a result downward facing fiber 1008 and detector 1302 arealigned with one another. As shown in FIG. 13D, optical fiber 1008 anddetector 1302 are then kept in aligned position using conventionaltechniques, such as optical epoxies, UV epoxies, for example.

[0072] Although the invention has been described with reference toexemplary embodiments, it is not limited thereto. Rather, the appendedclaims should be construed to include other variants and embodiments ofthe invention, which may be made by those skilled in the art withoutdeparting from the true spirit and scope of the present invention.

What is claimed is:
 1. A system for aligning a pair of optical fibers,the system comprising: an alignment tool located below a vision plane ofa first one of the pair of optical fibers; and an optical detector toreceive an indirect image of a bottom surface of the first one of thepair of optical fibers through the alignment tool.
 2. The systemaccording to claim 1, wherein an offset between the first one of thepair of optical fibers and the optical detector is determined based onthe indirect image of the first one of the pair of optical fibersreceived by the optical detector.
 3. The system according to claim 1,wherein the alignment tool is a counercube offset alignment tool.
 4. Thesystem according to claim 1, wherein optical detector is positionedabove a top surface of the alignment tool.
 5. The system according toclaim 1, wherein the alignment tool is formed from one of fused silica,sapphire, diamond, calcium fluoride and an optical glass.
 6. The systemaccording to claim 1, wherein the optical detector is a camera.
 7. Thesystem according to claim 6, wherein the camera is a CCD camera.
 8. Thesystem according to claim 1, wherein the optical detector is a CMOSimager.
 9. The system according to claim 1, wherein a vertex of thealignment tool is located at a position about midway between an opticalaxis of the optical detector and an optical axis of the first opticalfiber.
 10. The system according to claim 9, wherein a focal plane of thesystem is positioned above the vertex of the alignment tool.
 11. Thesystem according to claim 1, further comprising: a lens disposed betweenthe alignment tool and i) the optical detector and ii) the first one ofthe pair of optical fibers.
 12. The system according to claim 11,wherein the lens is a pair of lenses, a first lens of the pair of lensesdisposed between the alignment tool and the optical input means and asecond lens of the pair of lenses disposed between the alignment tooland the first optical fiber.
 13. The system according to claim 11,wherein the lens has a unitary magnification factor.
 14. The systemaccording to claim 1, wherein the alignment tool has an apex angle ofabout 90° and a second angle of about 45°.
 15. The system according toclaim 1, wherein the system is used with light having a wavelength inthe visible spectrum.
 16. The system according to claim 1, wherein thesystem is used with light having a wavelength between about 1-3000 nm.17. The system according to claim 1, wherein the system is used withlight having a wavelength between about 630-690 nm.
 18. The systemaccording to claim 1, wherein the system is used with light having awavelength between about 1-400 nm.
 19. The system according to claim 1,wherein the system is used with light having a wavelength between about700-3000 nm.
 20. The system according to claim 1, wherein the system isused with light having a wavelength of about 660 nm.
 21. The systemaccording to claim 1, further comprising: a lens positioned in both i) afirst optical axis between the optical detector and the alignment tooland ii) a second optical axis between the first optical fiber and thealignment tool, wherein the first and second optical axis aresubstantially parallel to one another.
 22. The system according to claim1, wherein the alignment tool has a plurality of internal reflectionsurfaces.
 23. A system for aligning a pair of optical fibers, the systemcomprising: an alignment tool located below a vision plane of a firstone of the pair of optical fibers; and an optical detector to receive i)an indirect image of a bottom surface of the first one of the pair ofoptical fibers through the alignment tool and ii) a direct image of atop section of a second one of the pair of optical fibers.
 24. Thesystem according to claim 23, wherein the alignment tool has a pluralityof internal reflection surfaces.
 25. A vision system for use with anoptical detector for aligning a pair of optical fibers, the systemcomprising: a cornercube offset tool located below a vision plane of afirst one of the pair of optical fibers; and a lens positioned in bothi) a first optical axis between the vision plane and the cornercubeoffset tool and ii) a second optical axis between the optical detectorand cornercube offset tool, wherein the optical detector receives atleast an indirect image of the first one of the pair of optical fibersthrough the cornercube offset tool.
 26. The cornercube offset toolaccording to claim 25, wherein the cornercube offset tool has aplurality of internal reflection surfaces.
 27. The cornercube offsettool according to claim 25, wherein the plurality of internal reflectionsurfaces are three internal reflection surfaces.
 28. A vision systemaccording to claim 25, wherein the optical detector is positioned abovethe image plane.
 29. A vision system according to claim 25, wherein thefirst optical axis and the second optical axis are substantiallyparallel to one another.
 30. The device according to claim 25, whereinthe lens has a unitary magnification factor.
 31. The device according toclaim 25, wherein the lens is a first lens positioned in the firstoptical axis and a second lens positioned in the second optical axis.32. The device according to claim 31, wherein the first lens and thesecond lens each have a unitary magnification factor.
 33. A visionsystem for aligning optical fibers, the system comprising: a cornercubeoffset tool located below a vision plane of the system; and an opticaldetector to receive an indirect image of the first one of the pair ofoptical fibers through the cornercube offset tool, wherein the opticalfibers are aligned with one another based on i) the indirect image of afirst one of the optical fibers and ii) a direct image of a second oneof the optical fibers received by the optical detector.
 34. A visionsystem according to claim 33, wherein the cornercube offset tool hasthree internal reflections.
 35. A vision system according to claim 33,wherein at least one of the internal reflection surfaces is a totalinternal reflection surface.
 36. A vision system according to claim 33,wherein the plurality of internal reflection surfaces are total internalreflection surfaces.
 37. A system for aligning optical fibers, thesystem comprising: image redirecting means disposed below a vision planeof a first one of the optical fibers; and detecting means to receive anindirect image of a bottom surface of the first one of the opticalfibers through the image redirecting means, wherein the first opticalfiber is aligned with a second optical fiber based on the indirect imagereceived by the detecting means.
 38. The system according to claim 37,wherein the image redirecting means has a plurality of internalreflection surfaces.
 39. A method for aligning a pair of optical fibers,the method comprising the steps of: providing a cornercube offset toolbelow a vision plane of a first one of the pair of optical fibers;viewing an indirect image of the first one of the pair of optical fiberswith an optical detector through the cornercube offset tool; determiningan offset between the first one of the pair of optical fibers and theoptical detector based on the indirect image; and aligning the first oneof the pair of optical fibers with a second one of the pair of opticalfibers based on the offset.
 40. The method according to claim 39,further comprising the steps of: reflecting internally an image of thefirst one of the pair of optical fibers, and providing the internallyreflected image for viewing by the optical detector.
 41. A system foraligning a pair of optical fibers, the system comprising: a cornercubeoffset tool having a plurality of internal reflection surfaces, thecornercube offset tool located below a vision plane of a first one ofthe pair of optical fibers; and an optical detector to receive anindirect image of the first one of the pair of optical fibers throughthe cornercube offset tool, wherein an offset between the first one ofthe pair of optical fibers and the optical detector is determined basedon the indirect image of the first one of the pair of optical fibers.42. The system according to claim 41, wherein the optical detectordetermines a position of a second one of the pair of optical fibersbased on receiving a direct image of the second one of the pair ofoptical fibers.
 43. The system according to claim 41, further comprisingrespective ones of an illumination system to illuminate a respectivefiber cladding of each of the pair of optical fibers.
 44. The systemaccording to claim 41, wherein the optical detector is positioned abovean upper surface of the cornercube offset tool.
 45. A system foraligning a pair of optical fibers, the system comprising: imageredirecting means disposed below a vision plane a first one of the pairof optical fibers, the image redirecting means having a plurality ofinternal reflection surfaces; and detecting means to receive an indirectimage of the first one of the pair of optical fibers through the imageredirecting means, wherein an offset between the first one of the pairof optical fibers and the detecting means is determined based on theindirect image of the first one of the pair of optical fibers.
 46. Amethod for use with an optical imager to align a pair of optical fibers,the method comprising the steps of: providing a cornercube offset toolbelow an end of a first one of the pair of optical fibers, thecornercube offset tool having three internal reflection surfaces;viewing an indirect image of the end of a first one of the pair ofoptical fibers with the optical imager through the cornercube offsettool; determining an offset distance of the first one of the pair ofoptical fibers; viewing a direct image of an end of a second one of thepair of optical fibers with the optical imager; and aligning the firstone of the pair of optical fibers with the second one of the pair ofoptical fibers.
 47. A system for aligning a plurality of optical fiberscontained in a fiber optic splitter bundle, the system comprising: analignment tool located below a vision plane of the fiber optic bundle;and an optical detector to receive an indirect image of a bottom surfaceof at least one of the plurality of optical fibers through the alignmenttool.
 48. A method for use with an optical imager to align opticalfibers, the method comprising the steps of: a) selecting a first opticalfiber from among a plurality of optical fibers from a fiber opticsplitter bundle; b) providing a cornercube offset tool below an end ofthe first optical fiber; c) viewing an indirect image of the end of thefirst optical fiber with the optical imager through the cornercubeoffset tool; d) determining an offset distance of the first opticalfiber; e) viewing a direct image of an end of a second optical fiberwith the optical imager; and f) aligning the first optical fiber withthe second optical fiber.
 49. The method according to claim 48, furthercomprising the steps of: g) selecting a further optical fiber from thefiber optic splitter bundle; h) repeating steps b) through f) for thefurther optical fiber and a third optical fiber.
 50. The methodaccording to claim 48, further comprising the step of coupling the firstoptical fiber with the second optical fiber.
 51. The method according toclaim 48, further comprising the steps of: g) bringing the end of thefirst optical fiber into contact with the end of the second opticalfiber; h) coupling the end of the first optical fiber into contact withthe end of the second optical fiber.
 52. The method according to claim48, further comprising the steps of: g) bringing the end of the firstoptical fiber into contact with the end of the second optical fiber; h)fusing the end of the first optical fiber into contact with the end ofthe second optical fiber.
 53. The method according to claim 52, whereinthe fusing step h) is accomplished by irradiating respective ends of theoptical fibers.
 54. A method for use with an optical imager to alignoptical fibers, the method comprising the steps of: a) providing acornercube offset tool below an end of a first optical fiber; b) viewingan indirect image of the end of the first optical fiber with an opticalimager through the cornercube offset tool; c) determining an offsetdistance of the first optical fiber; d) selecting a second optical fiberfrom among a plurality of optical fibers from a fiber optic splitterbundle; e) viewing a direct image of an end of a second optical fiberwith the optical imager; and f) aligning the first optical fiber withthe second optical fiber.
 55. The method according to claim 54, furthercomprising the steps of: g) providing a third optical fiber; h)selecting a further optical fiber from the fiber optic splitter bundle;i) repeating steps b) through f) for the third optical fiber and thefurther optical fiber.
 56. The method according to claim 54, furthercomprising the step of coupling the first optical fiber with the secondoptical fiber.
 57. The method according to claim 54, further comprisingthe steps of: g) bringing the end of the first optical fiber intocontact with the end of the second optical fiber; h) coupling the end ofthe first optical fiber into contact with the end of the second opticalfiber.
 58. The method according to claim 54, further comprising thesteps of: g) bringing the end of the first optical fiber into contactwith the end of the second optical fiber; h) fusing the end of the firstoptical fiber into contact with the end of the second optical fiber. 59.The method according to claim 58, wherein the fusing step h) isaccomplished by irradiating respective ends of the optical fibers.
 60. Asystem for aligning an optical fibers with an electronic device, thesystem comprising: an alignment tool located below a vision plane of afirst one of the pair of optical fibers; and an optical detector toreceive an indirect image of a bottom surface of the first one of thepair of optical fibers through the alignment tool.
 61. The systemaccording to claim 60, wherein the electronic device is a detector. 62.The system according to claim 60, wherein the electronic device is adiode.
 63. The system according to claim 60, wherein the electronicdevice is a photodiode.
 64. The system according to claim 60, whereinthe electronic device is an optical sensor.
 65. The system according toclaim 60, wherein the electronic device is an optical emitter.
 66. Thesystem according to claim 60, wherein the optical detector receives adirect image of the electronic device.
 67. A method for aligning anoptical fiber and a circuit element, the method comprising the steps of:providing a cornercube offset tool below a vision plane of the pair ofoptical fiber; viewing an indirect image of the optical fiber with anoptical detector through the cornercube offset tool; determining anoffset between the of optical fiber and the optical detector based onthe indirect image; and aligning the optical fibers with the circuitelement based on the offset.
 68. A method for use with an optical imagerto align an optical fiber and a circuit element, the method comprisingthe steps of: providing a cornercube offset tool below an end of theoptical fiber; viewing an indirect image of the end of the optical fiberwith the optical imager through the cornercube offset tool; determiningan offset distance of the optical fiber; viewing a direct image of asurface of the circuit element with the optical imager; and aligning theoptical fiber with the circuit element.